A new technique is used to monitor the primary afferent neural activity entering the spinal cord during normal walking. Fine wires implanted in the L7 and S1 dorsal root ganglia (DRG) of a cat record separable unit activity. Each unit is typically stable for 1-4 days, permitting correlation of unit activity with kinesiological records of normal and perturbed gait as well as accurate characterization of receptor modality under anesthesia. Neural and electromyographic activity is correlated with records of muscle force and joint angle from chronically implanted strain, length and EMG auges developed for this project. The reflex effects of various electrical stimuli to skin and muscles are systematically examined as they vary through the step cycle.